1. Field:
The present disclosure relates generally to aircraft and, in particular, to flight management control systems in aircraft. Still more particularly, the present disclosure relates to a method and apparatus for managing a flight control system in an aircraft.
2. Background:
An aircraft flight control system typically includes components, such as control surfaces, controllers in the cockpit, mechanisms to change the position of the flight control surfaces, and linkages connected to mechanisms that move the flight control surfaces. This type of flight control system provides a pilot with tactile and visual information regarding the position of the flight control surfaces. The tactile and visual information may occur through the orientation of the controllers in the cockpit.
Many pilots are familiar with the use of these types of mechanical control systems. As a result, this familiarity provides a pilot with a certain level of psychological assurance that the flight control system is operating correctly based on the tactile and visual information obtained from the position of the controllers.
This type of flight control system also provides tactile and visual information about the operation of the flight control surfaces through the controllers when an autopilot is engaged. For example, the autopilot system may be connected to the flight control system that is controlled through the use of actuators. These actuators are connected and parallel with the system's mechanical linkages. In this manner, the actuators move the flight control surfaces and controllers, such as the column, wheels, and pedals. These controllers are moved by the mechanical linkages as the flight control surfaces move.
A pilot may maintain an awareness of the operations performed by the autopilot based on the tactile and visual information provided by the position controllers. Some types of flight control systems, however, do not use mechanical linkages between the controllers and the flight control surfaces.
For example, one such flight control system is a fly-by-wire control system. With this type of flight control system, pilot command input through the controllers are converted into electrical signals by the controller. These signals are sent to a computer system that generates commands for control units that move the control surfaces. With this type of system, no linkages are present to move the controllers when the autopilot operates.
With this type of system, a backdrive system may also be included. The backdrive system has components that are configured to move the controllers to different positions during the operation of the autopilot to provide the tactile and visual information about the operation of the autopilot through the controllers. The backdrive system includes actuators associated with the controllers. The actuators receive signals from the computer system during operation of the autopilot. These signals cause the actuators to move the controllers in a manner that provides the tactile and visual information that may be desired by the pilot.
Thus, this type of flight control system also provides a capability for the pilot to disengage the autopilot through the pilot moving the controller. The backdrive system detects movement of the controller that is not generated by the autopilot. When this type of movement is detected, the autopilot is turned off, disconnected, or otherwise placed into a state in which the autopilot is not operating to direct movement of the aircraft. In this manner, the pilot of the aircraft regains control of the aircraft.
In some cases, if the backdrive system does not operate as desired, the control may move to a neutral position. This type of movement of the control is detected as the pilot moves the controller in a manner to override the autopilot. As a result, the autopilot stops operating the aircraft, and the pilot has to take over operation of the aircraft. In this manner, when the autopilot becomes unavailable, the workload of the pilot for operating the aircraft is increased. In this manner, the pilot may be unable to perform tasks, such as, for example, navigation, communications, and/or other tasks as desired.
Further, when the pilot operates the aircraft for longer periods of time than expected, the pilot may become fatigued. As a result, additional pilots or crew members may be needed in the aircraft to take into account these types of situations, depending on the mission being performed by the aircraft.
One manner in which this type of situation may be avoided is using additional actuators as back-ups to the actuators used to move the controllers to provide the tactile and visual information. In other words, each actuator in the backdrive system has one or more additional actuators that perform the same function in case the actuator fails to operate as desired. In this manner, redundancy reduces situations in which the autopilot becomes disengaged or stops operating the aircraft.
In this type of system, however, the use of additional actuators and wiring for the additional actuators increases the weight and cost of an aircraft. Also, with additional actuators, more space is needed in the aircraft to accommodate these actuators. Further, additional maintenance may be needed to replace or inspect the actuators. The increased weight, cost, space used, and/or maintenance may be undesirable.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above, as well as possibly other issues.